I'm a little curious, but I am very attached to Adblock Plus, NoScript, and IETab, which I use in Firefox. My wireless setup means that I probably wouldn't notice any speed difference, but still it wouldn't hurt to try something new. I'll be curious to hear your impressions.

I don't keep up with FF add ons, so I'm nt certain exactly what the ones that you refer to mean, but IETab sound similar to a button that I add to Opera to open IE at whatever page that I'm viewing in Opera. Instead of just a tab, IE itself opens. I have a similar button for FF. Adblock Plus sounds something like Opera's ability to block websites listed in a custom urlfilter.ini.

You can also set individual site preferences to have pages display in the fashion that you want. I can't make a detailed list of differences between the browsers, but I believe that anything FF can do, Opera can do, except in a different fashion. I can say the same thing for FF, because there are a lot of things that FF can't do, that Opera does.